Individual disk-shaped red blood cells appear colorless when viewed under a microscope. The pink tint on the left of the image is due to clotting of several layers of red blood cells.

A drop of blood was diluted in saline solution, then sandwiched between a slide and coverslip (using a thin strip of silicon rubber as a spacer). The image was taken on an inverted compound microscope using a 40x DIC objective and a digital camera.

Supported by a Science Education Partnership Award (SEPA) from the National Center for Research Resources, National Institutes of Health, and the David and Lucile Packard Foundation.